United States
Environmental Protection
Agency
Office of Water
Regulations and Standards
Washington, DC 20460
Water
June. 198?
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PREFACE
This document is one of a series of preliminary assessments dealing
with chemicals of potential concern in municipal sewage sludge. The
purpose of these documents is to: (a) summarize the available data for
the constituents of potential concern, (b) 'identify the key environ-
mental pathways for each constituent related to a reuse and disposal
option (based on hazard indices), and (c) evaluate the conditions under
which such a pollutant may pose a hazard. Each document provides a sci-
entific basis for making an initial determination of whether a pollu-
tant, at levels currently observed in sludges, poses a likely hazard to
human health or the environment when sludge is disposed of by any of
several methods. These methods include landspreading on food chain or
nonfood chain crops, distribution and marketing programs, landfilling,
incineration and ocean disposal.
These documents are intended to serve as a rapid screening tool to
narrow an initial list of pollutants to those of concern. If a signifi-
cant hazard is indicated by this preliminary analysis, a more detailed
assessment will be undertaken to better quantify the risk from this
chemical and to derive criteria if warranted. If a hazard is shown to
be unlikely, no further assessment will be conducted at this time; how-
ever, a reassessment will be conducted after initial regulations are
finalized. In no case, however, will criteria be derived solely on the
basis of information presented in this document.
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TABLE OP CONTENTS
Page
PREFACE i
1. INTRODUCTION . 1-1
2. PRELIMINARY CONCLUSIONS FOR VINYL CHLORIDE IN MUNICIPAL
SEWAGE SLUDGE 2-1
Landspreading and Distribution-and-Marketing 2-1
Landfilling 2-1
Incineration 2-1
Ocean Disposal 2-1
3. PRELIMINARY HAZARD INDICES FOR VINYL CHLORIDE IN MUNICIPAL
SEWAGE SLUDGE 3-1
Landspreading and Distribution-and-Marketing 3-1
Landf illing 3-1
Incineration 3-1
Index of air concentration increment resulting
from incinerator emissions (Index 1) 3-1
Index of human cancer risk resulting from
inhalation of incinerator emissions (Index 2) 3-4
Ocean Disposal 3-6
4. PRELIMINARY DATA PROFILE FOR VINYL CHLORIDE IN MUNICIPAL
SEWAGE SLUDGE 4-1
Occurrence 4-1
Sludge 4-1
Soil - Unpolluted 4-1
Water - Unpolluted 4-1
Air 4-1
Food 4-2
Human Effects 4-2
Ingestion 4-2
Inhalation 4-3
Plant Effects 4-4
11
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TABLE OF CONTENTS
(Continued)
Page
Domestic Animal and Wildlife Effects 4-4
Aquatic Life Effects 4-4
Soil Biota Effects 4-4
Physicochemical Data for Estimating Fate and Transport 4-4
5. REFERENCES 5-1
APPENDIX. PRELIMINARY HAZARD INDEX CALCULATIONS FOR
VINYL CHLORIDE IN MUNICIPAL SEWAGE SLUDGE A-l
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SECTION 1
INTRODUCTION
This preliminary data profile is one of a series of profiles
dealing with chemical pollutants potentially of concern in municipal
sewage sludges. Vinyl chloride was initially identified as being of
potential concern when sludge is incinerated.* This profile is a compi-
lation of information that may be useful in determining whether vinyl
chloride poses an actual hazard to human health or the environment when
sludge is disposed of by this method.
The focus of this document is the calculation of "preliminary
hazard indices" for selected potential exposure pathways, as shown in
Section 3. Each index illustrates the hazard that could result from
movement of a" pollutant by a given pathway to cause a given effect
(e.g., sludge •* air -*• human toxicity). The values and assumptions
employed in these calculations tend to represent a reasonable "worst
case"; analysis of error or uncertainty has been conducted to a limited
degree. The resulting value in most cases is indexed to unity; i.e.,
values >1 may indicate a potential hazard, depending upon the
assumptions of the calculation.
The data used for index calculation have been selected or estimated
based on information presented in the "preliminary data profile",
Section 4. Information in the profile is based on a compilation of the
recent literature. An attempt has been made to fill out the profile
outline to the greatest extent possible. However, since this is a pre-
liminary analysis, the literature has not been exhaustively perused.
The "preliminary conclusions" drawn from each index in Section 3
are summarized in Section 2. The preliminary hazard indices will be
used as a screening tool to determine which pollutants and pathways may
pose a hazard. Where a potential hazard is indicated by interpretation
of these indices, further analysis will include a more detailed exami-
nation of potential risk.s as well as an examination of site-specific
factors. These more rigorous evaluations may change the preliminary
conclusions presented in Section 2, which are based on a reasonable
"worst case" analysis.
The preliminary hazard indices for selected exposure routes
pertinent to incineration practices are included in this profile. The
calculation formulae for these indices are shown in the Appendix. The
indices are rounded to two significant figures.
* Listings were determined by a series of expert workshops convened
during March-May, 1984 by the Office of Water Regulations and
Standards (OWRS) to discuss landspreading, landfilling, incineration,
and ocean disposal, respectively, of municipal sewage sludge.
1-1
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SECTION 2
PRELIMINARY CONCLUSIONS FOR VINYL CHLORIDE IN MUNICIPAL SEWAGE SLUDGE
The following preliminary conclusions have been derived from the
calculation of "preliminary hazard indices", which represent conserva-
tive or "worst case" analyses of hazard. The indices and their basis
and interpretation are explained in Section 3. Their calculation
formulae are shown in the Appendix.
I. LANDSPREADING AND DISTRIBUTION-AND-MARKETING
Based on the recommendations of the experts at the OWRS meetings
(April-May, 1984), and assessment of this reuse/disposal option is
not being, conducted at this time. The U.S. EPA reserves the right
to conduct such an assessment for this option in the future.
II. LANDFILLING
Based on the recommendations of the experts at the OWRS meetings
(April-May, 1984), and assessment of this reuse/disposal option is
not being conducted at this time. The U.S. EPA reserves the right
to conduct such an assessment for this option in the future.
III. INCINERATION
The concentration of vinyl chloride in air is not expected to
increase above the background concentration when most vinyl
chloride-contaminated sludges are incinerated. A slight increase
above the background concentration is expected only when worst-case
conditions prevail (see Index 1).
The incineration of vinyl chloride-contaminated sludges will not,
in most cases, increase the risk of cancer above the pre-existing
risk attributable to background concentration. A potential
increase in the risk of cancer (of about 1 per 100,000) is
indicated only when worst-case conditions are assumed for all
parameters (see Index 2).
IV. OCEAN DISPOSAL
Based on the recommendations of the experts at the OWRS meetings
(April-May, 1984), and assessment of this reuse/disposal option is
not being conducted at this time. The U.S. EPA reserves the right
to conduct such an assessment for this option in the future.
2-1
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SECTION 3
PRELIMINARY HAZARD INDICES FOR VINYL CHLORIDE
IN MUNICIPAL SEWAGE SLUDGE
I. LANDSPREADING AND DISTRIBUTION-AND-MARKETING
Based on the recommendations of the experts at the OWRS meetings
(April-May, 1984), an assessment of this reuse/disposal option is
not being conducted at this time. The U.S. EPA reserves the right
to conduct such an assessment for this option in the future.
II. LANDPILLlNG
Based on- the recommendations of the experts at the OWRS meetings
(April-flay, 1984), an assessment of this reuse/disposal option is
not being conducted at this time. The U.S; EPA reserves the right
to conduct such an assessment for this option in the future.
III. INCINERATION
A. Index of Air Concentration Increment Resulting from
Incinerator Emissions (Index 1)
1. Explanation - Shows the degree of elevation of the
pollutant concentration in the air due to the incinera-
tion of sludge. An input sludge with thermal properties
defined by the energy parameter (EP) was analyzed using
the BURN model (Camp Dresser and McKee, Inc. (CDM),
1984). This model uses the thermodynamic and mass
balance relationships appropriate for multiple hearth
incinerators to relate the input sludge characteristics
to the stack, gas parameters. Dilution and dispersion of
these stack gas releases were described by the U.S. EPA's
Industrial Source Complex Long-Term (ISCLT) dispersion
model from which normalized annual ground level concen-
trations were predicted (U.S. EPA, 1979).' The predicted
pollutant concentration can then be compared to a ground
level concentration used to assess risk.
•
2. Assumptions/Limitations - The fluidized bed incinerator
was not chosen due to a paucity of available data.
Gradual plume rise, stack tip downwash, and building wake
effects are appropriate for describing plume behavior.
Maximum hourly impact values can be translated into
annual average values.
3. Data Used and Rationale
a. Coefficient to correct for mass and time units (C) =
2.78 x 10~7 hr/sec x g/mg
3-1
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b. Sludge feed rate (DS)
i. Typical = 2660 kg/hr (dry solids input)
A feed rate of 2660 kg/hr DW represents an
average dewatered sludge feed rate into the
furnace. This feed rate would serve a commun-
ity of approximately 400,000 people. This rate
was incorporated into the U.S. EPA-ISCLT model
based on the following input data:
EP = 360 Ib H20/mm BTU
Combustion zone temperature - 1400°F
Solids content - 28%
Stack height - 20 m
Exit gas velocity - 20 m/s
Exit gas temperature - 356.9°K (183°F)
Stack diameter - 0.60 m
ii. Worst = 10,000 kg/hr (dry solids input)
A feed rate of 10,000 kg/hr DW represents a
higher feed rate and would serve a major U.S.
city. This rate was incorporated into the U.S.
EPA-ISCLT model based on the following input
data:
EP = 392 Ib H20/mm BTU
Combustion zone temperature - 1400°F
Solids content - 26.6%
Stack height - 10 m
Exit gas velocity - 10 m/s
Exit gas temperature - 313.8°K (105°F)
Stack diameter - 0.80 m
c. Sludge concentration of pollutant (SC)
Typical 0.43 mg/kg DW
Worst 311.94 mg/kg DW
The typical and worst case concentrations are the
geometric mean and 95th percentile, respectively,
statistically derived from sludge concentration data
from a survey of 40 publicly owned treatment works
(POTWs) (U.S. EPA, 1982). (See Section 4, p. 4-1.)
d. Fraction of pollutant emitted through stack (FM)
Typical 0.05 (unitless)
Worst 0.20 (unitless)
These values were chosen as best approximations of
the fraction of pollutant emitted through stacks
(Farrell, 1984). No data was available to validate
3-2
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these values; however, U.S. EPA is currently testing
incinerators for organic emissions.
Dispersion parameter for estimating maximum annual
ground Level concentration (DP)
Typical 3.4
Worst 16.0 ug/m3
The dispersion parameter is derived from the U.S.
EPA-ISCLT short-stack model.
f. Background concentration of pollutant in urban
air (BA) = 43.316 Ug/m3
The average concentration of vinyl chloride in air
within a 5 mile radius of a polyvinyl chloride or
vinyl chloride plant was calculated to be 17 ppb
(U.S. EPA, 1980). This value was used to calculate
the concentration given above because it represents
the expected air concentration where vinyl chloride
is used in industry and would, thus, be a possible
pollutant in sludge. This value was the only data
immediately available.
The value, 17 ppb, was converted to Ug/m3 of air by
multiplying by the vapor density of vinyl chloride
relative to air (Sax, 1984) and the appropriate unit
conversions. (See Section 4, pp. 4-1 to 4-2.)
4. Index 1 Values
Sludge Feed
Fraction of - Rate (kg/hr DW)a
Pollutant Emitted Sludge
Through Stack Concentration 0 2660 10,000
Typical
Typical
Worst
1.0
1.0
1.0
1.0
1.0
1.0
Worst Typical 1.0 1.0 1.0
Worst 1.0 1.0 1.1
a The typical (3.4 ug/m^) and worst (16.0 ug/m3) disper-
sion parameters will always correspond, respectively,
to the typical (2660 kg/hr DW) and worst (10,000 kg/hr
DW) sludge feed rates.
5. Value Interpretation - Value equals factor by which
expected air concentration exceeds background levels due
to incinerator emissions.
3-3
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6. Preliminary Conclusion - The concentration of vinyl
chloride in air is not expected to increase above the
background concentration when most vinyl chloride-
contaminated sludges are incinerated. A slight increase
above the background concentration is expected only when
worst-case conditions prevail.
B. Index of Human Cancer Risk Resulting from Inhalation
of Incinerator Emissions (Index 2)
1. Explanation - Shows the increase in human intake expected
to result from the incineration of sludge. Ground level
concentrations for carcinogens typically were developed
based upon assessments published by the U.S. EPA Carcino-
gen Assessment Group (CAG). These ambient concentrations
- reflect a dose level which, for a lifetime exposure,
increases the risk of cancer by 10~^. For non-
carcinogens, levels typically were derived from the Amer-
ican Conference of Government Industrial Hygienists
(ACGIH) threshold limit values (TLVs) for the workplace.
2. Assumptions/Limitations - The exposed population is
assumed to reside within the impacted area for 24
hours/day. A respiratory volume of 20 m-Vday is assumed
over a 70-year lifetime.
3. Data Used and Rationale
a. Index of air concentration increment resulting from
incinerator emissions (Index 1)
See Section 3, p. 3-3.
b. Background concentration of pollutant in urban air
(BA) = 43.316 Ug/m3
See Section 3, p. 3-3.
c. Cancer potency = 1.74 x 10"^ (mg/kg/day)"^-
The cancer potency value was derived from studies in
which rats were exposed to a range of vinyl chloride
levels in air. The effect of concern in these
studies was hepatic angiosarcoma (U.S. EPA, 1980).
(See Section 4, p. 4-2.)
d. Exposure criterion (EC) = 0.20 ug/m^
A lifetime exposure level which would result in a
10~6 cancer risk was selected as ground level
concentration against which incinerator emissions
are compared. The risk estimates developed by CAG
are defined as the lifetime incremental cancer risk
in a hypothetical population exposed continuously
3-4
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throughout their lifetime to the stated
concentration of the carcinogenic agent. The
exposure criterion is calculated using the following
formula: •
_ 10"6 x 103 ug/mg x 70 kg
t.C - — ^
Cancer potency x 20 mj/day
4. Index 2 Values
Sludge Feed
Fraction of Rate (kg/hr DW)a
Pollutant Emitted Sludge
Through Stack Concentration 0 2660 10,000
Typical Typical 220 220 220
Worst 220 220 220
Worst Typical 220 220 220
Worst 220 220 230
a The typical (3.4 ug/nr*) and worst (16.0 Ug/m3) disper-
sion parameters will always correspond, respectively,
to the typical (2660 kg/hr DW) and worst (10,000 kg/hr
DW) sludge feed rates.
5. Value Interpretation - Value > 1 indicates a potential
increase in cancer risk of > 10~6 (1 per 1,000,000).
Comparison with the null index value at 0 kg/hr DW
indicates the degree to which any hazard is due to sludge
incineration, as opposed to background urban air
concentration.'
6. Preliminary Conclusion - The incineration of vinyl
chloride-contaminated sludges will not, in most cases,
increase the risk of cancer above the pre-existing risk
attributable to the background concentration. A poten-
tial increase in the risk of cancer (of about 1 per
100,000) is indicated only when worst-case conditions are
assumed for all parameters.
IV. OCEAN DISPOSAL
Based on the recommendations of the experts at the OWES meetings
(April-May, 1984), an assessment of this reuse/disposal option is
not being conducted at this time. The U.S. EPA reserves the right
to conduct such an assessment for this option in the future.
3-5
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SECTION 4
PRELIMINARY DATA PROFILE FOR VINYL CHLORIDE IN MUNICIPAL SEWAGE SLUDGE
I. OCCURRENCE
A. Sludge
B.
1. Frequency of Detection
33 of 477 samples (7%) from 50 POTWs
contained detectable levels of vinyl
chloride
2. -Concentration
For 13 POTWs reporting analyses for
vinyl chloride, the following results
were found:
Minimum: not detected
not detected
0.43 mg/kg DW
69.82 mg/kg DW
311.94 mg/kg DW
686.54 mg/kg DW
Median:
Geometric mean:
Arithmetic mean:
95th percentile:
Maximum:
Soil - Unpolluted
Vinyl chloride does not occur in nature.
U.S. EPA, 1982
(pp. 42, 50)
Values
statistically-
derived from
U.S. EPA, 1982
C. Hater - Unpolluted
No evidence of vinyl chloride in unpolluted
environments
D. Air
1. Frequency of Detection
•
Data not immediately available.
2. Concentration
a. Urban
The average concentration within a
5-mile radius of a polyvinyl chloride
or vinyl chloride plant was
calculated to be 17 ppb.
NAS, 1977
(p. 783)
U.S. EPA, 1980
(p. C-2)
U.S. EPA, 1980
(p. C-54)
4-1
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17 ppb was converted to 43.316
by using the vapor density of
2.15 for vinyl chloride relative to Sax» 1984
air and appropriate unit conversions.
b. Rural
Data not immediately available.
E. Food
1. Total average intake
Data not immediately available.
2. - Concentration
Vinyl chloride has been found in foods U.S. EPA, 1980
packaged in polyvinyl chloride wraps (p. C-7)
and containers, especially alcoholic
beverages, oils, and cider or vinegar.
Product Type Range (ug/mL)
Alcoholic beverages 0.025 to 1.60
Vegetable oil 0.3 to 3.29
Cider or vinegar ND to 8.40
II. HUMAN EFFECTS
A. Ingestion
1. Carcinogenicity
a. Qualitative Assessment
Data for humans are not immediately U.S. EPA, 1980
available, but at least one study (p. C-36)
using rats indicates that vinyl
chloride is carcinogenic when
ingested.
b. Potency
Cancer Potency = 1.4 x 10"1 U.S. EPA, 1984
(mg/kg/day)'1 (p. 35)
c. Effects
In the study using rats, U.S. EPA, 1980
angiosarcomas of the liver and (p. C-36)
thymus gland were noted.
4-2
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2. Chronic Toxicity
Data not presented because cancer
potency will be used to assess hazard.
3. Absorption Factor
Data not immediately available.
4. Existing Regulations
Interim U.S. EPA target risk levels and U.S. EPA, 1980
the corresponding water quality criteria (p. C-61)
(assuming average daily consumption of
2 L drinking water and 6.5 g of fish and
shellfish)
Risk Level Criteria (yg/L)
10~7 0.2
10~6 2.0
ID'5 20
B. Inhalation
1. Carcinogenicity
a. Qualitative Assessment
Viny chloride has been shown to be U.S. EPA, 1984
carcinogenic when inhaled.
b. Potency
Cancer potency = 1.74 x 10~2 U.S. EPA, 1980
(mg/kg/day)"1 (p. C-82)
c. Effects
Vinyl chloride has caused significant U.S. EPA, 1984
increases in the incidence of hepatic (p. 12)
angiosarcomas, and has been
implicated as a causal factor in
increased incidences of lung, brain,
breast, pancreatic, and other tumors
among polyvinyl chloride and vinyl
chloride workers.
4-3
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2. Chronic Toxicity
a. Inhalation Threshold or MPIH
10 mg/m3 time weighted average (TWA)
b. Effects
Angioneurosis, dermatitis, acro-
osteolysis, hepatomegaly, spleno-
megaly, liver fibrosis, thrombocyto-
penia, and others
3. Absorption Factor
In rats, vinyl chloride has been
reported to be absorbed rapidly from
the lungs into the bloodstream.
4. Existing Regulations
10 mg/m3 TWA
2.6 mg/m3 8-hour TWA
13 mg/m3 average over any period
<15 minutes
III. PLANT EFFECTS
Data not immediately available.
IV. DOMESTIC ANIMAL AND WILDLIFE EFFECTS
Data not immediately available.
V. AQUATIC LIFE EFFECTS
Data not immediately available.
VI. SOIL BIOTA EFFECTS
Data not immediately available.
American
Conference
of
Governmental
Industrial
Uygienists
(ACGIH), 1983
U.S. EPA, 1984
(p. 7)
U.S. EPA, 1984
(p. 2)
ACGIH, 1983
Occupational
Safety and
Health Admini-
stration (Code
of Fed. Reg.,
1981) as cited
by U.S. EPA,
1984 (p. 30)
4-4
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VII. PHYSICOCHEMICAL DATA FOR ESTIMATING FATE AND TRANSPORT
Chemical composition:
Molecular weight:
Vapor density
relative to air:
Water solubility:
CH2CHC1
62.5
2.15
2760 mg/L at 25°C
1100 mg/kg at 28°C
Octonol/water partition
coefficient: 24 (estimated)
Bioconcentration
factor:
Half-life
Air: -
Water:
2.97 (estimated)
1.2 days
1 to 5 days (estimated)
Sax, 1984
U.S. EPA, 1984
U.S. EPA, 1984
U.S. EPA, 1984
U.S. EPA, 1984
4-5
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SECTION 5
REFERENCES
American Conference of Governmental Industrial Hygienists. 1983.
Threshold Limit Values for Chemical Substances and Physical Agents
in the Work Environment with Intended Changes for 1983-84. Second
Printing. ACGIH, Cincinnati, OH. 93 pp.
Camp Dresser and McKee, Inc. 1984. Development of Methodologies for
Evaluating Permissible Contaminant Levels in Municipal Wastewater
Sludges. Draft. Office of Water Regulations and Standards, U.S.
Environmental Protection Agency, Washington, D.C.
Farrell, J. B." 1984. Personal Communication. Water Engineering
Research Laboratory, U.S. Environmental Protection Agency,
Cincinnati, OH. December.
National Academy of Sciences. 1977. Drinking Water and Health.
National Academy of Sciences, Washington, D.C. 939 pp.
Sax, N. I. 1984. Dangerous Properties of Industrial Materials. Sixth
Edition. Van Nostrand Reinhold Co., Inc., New York, NY.
U.S. Environmental Protection Agency. 1.979. Industrial Source Complex
(ISC) Dispersion Model User Guide. EPA 450/4-79-30. Vol. 1.
Office of Air Quality Planning and Standards, Research Triangle
Park, NC. December.
U.S. Environmental Protection Agency. 1980. Ambient Water Quality Cri-
teria for Vinyl Chloride. EPA 440/5-80-078. Office of Water
Regulations and Standards, Criteria and Standards Division,
Washington, D.C. October.
U.S. Environmental Protection Agency. 1982. Fate of Priority Pollu-
tants in Publicly-Owned Treatment Works. Final Report. Volume 1.
EPA 440/1-82-303. Effluent Guidelines Division, Washington, D.C.
September.
U.S. Environmental Protection Agency. 1984. Health Effects Assessment
for Vinyl Chloride. ECAO-CIN-H036. Environmental Criteria and
Assessment Office, Cincinnati, OH. November.
5-1
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APPENDIX
PRELIMINARY HAZARD INDEX CALCULATIONS FOR VINYL CHLORIDE
IN MUNICIPAL SEWAGE SLUDGE
I. LANDSPREADING AND DISTRIBUTION-AMD-MARKETING
Based on the recommendations of the experts at the OWRS meetings
(April-May, 198A), an assessment of this reuse/disposal option is
not being conducted at this time. The U.S. EPA reserves the right
to conduct such an assessment for this option in the future.
II. LANDPILLING
Based on' the recommendations of the experts at the OWRS meetings
(April-May, 198A), an assessment of this reuse/disposal option is
not being conducted at this time. The U.S. EPA reserves the right
to conduct such an assessment for this option in the future.
III. INCINERATION
A. Index of Air Concentration Increment Resulting from Incinerator
Emissions (Index 1)
1. Formula
T ., 1 (C x PS x SC x FM x DP) + BA
Index 1 = —
where:
C = Coefficient to correct for mass and time units
(hr/sec x g/mg)
DS = Sludge feed rate (kg/hr DW)
SC = Sludge concentration of pollutant (mg/kg DW)
FM = Fraction of pollutant emitted through stack
(unitless)
DP = Dispersion parameter for estimating maximum
annual ground level concentration (pg/m3)
BA = Background concentration of pollutant in urban
air (ug/m3)
2. Sample Calculation
1.0 = [(2.78 x 10"7 hr/sec x g/mg x 2660 kg/hr DW x 0.43 mg/kg DW x 0.05
x 3.4 wg/m3) + 43.316 yg/m3] * 43.316 ug/m3
A-l
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B. Index of Human Cancer Risk Resulting from Inhalation of
Incinerator Emissions (Index 2)
1. Formula
! - 1.) x BA] + BA
Index 2 =
EC
where:
II = Index 1 = Index of air concentration increment
resulting from incinerator emissions
(unitless)
BA = Background concentration of pollutant in
urban air (ug/m3)
EC = Exposure criterion (yg/m3)
2. Sample Calculation
216 58 _ f(1.0 - 1) x A3. 316 Ug/m3] * 43.316 ug/m3
0.20
IV. OCEAN DISPOSAL
Based on the recommendations of the experts at the OWRS meetings
(April-May, 1984), an assessment of this reuse/disposal option is
not being conducted at this time. The U.S. EPA reserves the right
to conduct such an assessment for this option in the future.
A-2
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